What Is 5,5'-Bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-2,2'-bithiophene?

5,5'-Bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-2,2'-bithiophene (SKU B152913) is a symmetrical organoboron compound in which both terminal α-positions (5 and 5') of the 2,2'-bithiophene unit carry a pinacol boronate ester (Bpin) group. The pinacol ester protects the boronic acid functionality, improving stability toward air and moisture relative to the free boronic acid, while retaining high reactivity in palladium-catalysed cross-coupling chemistry.

The 2,2'-bithiophene core is a well-established π-conjugated motif found in a broad range of organic electronic and optoelectronic materials. The bifunctional nature of this compound — two reactive boron handles on a single conjugated scaffold — makes it an A–A type monomer suitable for step-growth polymerisation with complementary dihalide (B–B) monomers, or for sequential coupling to build defined oligomeric structures.

Key Physical and Chemical Properties

The compound has the molecular formula C₂₀H₂₈B₂O₄S₂ and a molecular weight of approximately 450.18 g/mol. The molecule is a crystalline solid at room temperature. The bithiophene backbone confers a degree of planar conjugation, and the pinacol boronate groups are the sites of transmetalation in Suzuki–Miyaura catalytic cycles.

The pinacol boronate ester form exhibits improved bench stability compared with free boronic acids and is generally less susceptible to protodeboronation under mildly acidic conditions. Solubility is good in common organic solvents such as tetrahydrofuran (THF), dichloromethane, toluene, and dimethylformamide (DMF), facilitating use in both small-molecule synthesis and polymerisation protocols.

Note: Specific melting point, solubility values, and spectroscopic data (NMR, UV-Vis) should be verified against the certificate of analysis (CoA) supplied with each lot.

Applications in Organic and Polymer Chemistry

Suzuki–Miyaura Cross-Coupling: The primary application of this compound is as a bis-boronate ester monomer in palladium-catalysed Suzuki–Miyaura polycondensation. When coupled with aromatic or heteroaromatic dihalide partners (e.g., dibrominated electron-deficient units), it yields π-conjugated copolymers used in organic field-effect transistors (OFETs), organic photovoltaics (OPVs), and organic light-emitting diodes (OLEDs).

Defined Oligomer Synthesis: The compound can be used in stepwise coupling sequences to produce well-defined oligothiophene or mixed heteroacene structures for structure–property relationship studies.

Sensor and Optoelectronic Materials: Bithiophene-containing conjugated materials derived from this monomer have been explored for chemical sensing, electrochromic devices, and thin-film transistor applications, owing to the favourable charge-transport properties of the thiophene-based backbone.

Academic Research: It is widely used as a model bifunctional monomer to study polymerisation kinetics, molecular weight control, and end-group analysis in conjugated polymer synthesis.

Storage, Handling, and Safety

Storage: The compound should be stored in a cool, dry, well-ventilated location, away from light and moisture. Storage under an inert atmosphere (nitrogen or argon) in a sealed container is recommended to prevent slow hydrolysis of the boronate ester groups over extended periods. Refrigeration at 2–8 °C is typically advisable for long-term preservation of purity.

Handling: Standard laboratory precautions apply: use appropriate personal protective equipment (PPE) including gloves, safety glasses, and a lab coat. Reactions involving this compound are typically conducted under inert atmosphere (Schlenk technique or glovebox) to exclude moisture and oxygen, which can affect catalytic performance in cross-coupling reactions.

Disposal: Dispose of waste in accordance with local regulations governing organoboron and organosulfur compounds. Do not pour down the drain without checking local effluent guidelines.

Note: A full Safety Data Sheet (SDS) should be consulted before use. Specific hazard classifications should be verified on the current SDS provided by Aladdin Scientific.

Ordering and Specifications

5,5'-Bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-2,2'-bithiophene is available from Aladdin Scientific under SKU B152913. Researchers should request the current certificate of analysis (CoA) to confirm purity, lot-specific analytical data (e.g., HPLC, NMR), and physical constants before use in critical applications.

For bulk quantities, custom purity grades, or procurement enquiries, please contact Aladdin Scientific's sales team. Volume pricing and institutional account options may be available.

Ensure that the correct product is selected by verifying the CAS number (190788-63-7) and molecular formula (C₂₀H₂₈B₂O₄S₂) against your synthetic requirements prior to ordering.